This research program is designed to isolate and purify biologically active Proinsulin mRNA. This study will be carried out in the following manner: (a) Isolation of crude polysomal RNA from a suitable tissue synthesizing insulin; (b) Initial purification of this RNA by oligo (dT) cellulose chromatography followed by subsequent purification steps using sucrose gradient fractionation; (c) Translation of the purified mRNA in a cell-free system derived from ascites tumor cell; (d) Attempts at identifying the products as proinsulin with procedures involving immunological techniques and published methods for protein and peptide analyses. Another aim is to quantitate the levels of proinsulin mRNA in isolated islets using the radioactive DNA transcript of proinsulin mRNA and sensitive hybridization techniques. The radioactive DNA will be prepared from purified proinsulin mRNA with the reverse transcriptase purified from avian myeloblastosis virus. The question of how glucose stimulants proinsulin synthesis, for example, can then be examined. It is believed that having in hand purified proinsulin mRNA will provide insight as to (a) the molecular mechanisms by which a select class of effector molecules stimulate insulin synthesis and (b) the possible involvement of such effects in disease.